This invention relates to a seal arrangement for two intersecting conduits in which one conduit is sealed from the other. The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.
In an engine for rocket vehicle propulsion, a nuclear reactor is utilized to heat a propellant, generally liquid hydrogen, causing it to be converted to a gas which is expanded through a nozzle thereby creating a propulsive thrust. Centrally located within the reactor is a group of bundled fuel elements called the "core". Surrounding the core of the reactor is an open-ended cylindrical housing, hereinafter referred to as a "reflector." The reflector is used to reflect escaping neutrons back into the core thereby permitting the reactor to operate with a smaller fuel load. Beryllium is utilized as a reflector material which because of its high thermal stress and brittleness must be uniformly cooled during reactor operation. One method of cooling is the passing of the hydrogen propellant through coolant conduits within the reflector housing in a heat transfer relationship. In order to assure uniform cooling in the inner periphery of the reflector nearest the reactor core, axially aligned, equally spaced apart conduits are located within and along the inner peripheral section of the reflector. Spring loaded, graphite plungers, or retaining pins, utilized to position the reactor core pass through the reflector in a direction normal to the reflector axis. Because of the small spacing between and the relatively large diameter of the peripheral coolant conduits, there is an intersection between a peripheral coolant conduit and a retaining pin conduit both of which lie within the reflector.
In previous designs coolant passing through the peripheral conduit would seep around the retaining pin and into the retaining pin conduit and, further, into and around the core region of the rocket engine. This seepage or loss of coolant into the core region results in loss of performance and regions of thermal stress around the core. One suggested solution considered to reduce the coolant seepage around the retaining pins was to eliminate those coolant conduits which would intersect the retaining pin conduit. Although this necessarily would prevent any seepage, the elimination of the conduit would cause an undesirable hot spot in the beryllium reflector due to a lack of uniform heat transfer. With the necessity for maintaining the intersecting coolant conduit, effort was then directed to the sealing of the retaining pin conduit in a manner that would allow continuous coolant flow around the graphite pin without coolant seepage into the pin conduit.